The $17.5 million project focuses on I-78 between the Morgan Hill Road interchange and the toll bridge in Williams Township. Substantial completion is expected by May 15, with remaining work to be finished about a month later.

Westbound and eastbound lane closures are slated to begin toward the end of next week.

The project calls primarily for single-lane closures during daytime hours with an additional lane closed at night when traffic volumes are lowest, the commission said. The project is staged to keep at least two lanes open in each direction during peak travel periods.

“This is one of the busiest truck corridors in the United States and this work will build upon the investments the agency made in rehabilitating the commission’s I-78 New Jersey segment three years ago and implementing Express E-ZPass at the I-78 toll plaza two years ago,” commission acting Executive Director Frank J. Tolotta said in a statement. “It’s our goal to carry out this project while keeping commuter traffic and commercial shipments moving as much as possible.”

A 45-mph speed limit will be in effect in the construction zone.

Known as the I-78 Toll Bridge PA Approach Paving Improvements Project, the work includes:

Rehabilitation and repaving of existing concrete pavements in both the eastbound and westbound directions along the commission’s Pennsylvania segment of I-78.

Paving and miscellaneous improvements to the parking facilities for the Pennsylvania Welcome Center and the commission’s I-78 maintenance facility adjacent to the westbound toll plaza in Williams Township.

Improvements to bridge decks, joints and approach slabs, including the main river I-78 Toll Bridge -- it consists of two separate parallel structures -- and 11 secondary bridge structures (overpasses and underpasses) east and west along I-78.